Bag filters are typically formed from sheets of flexible material which are joined together, usually by sewing such sheets together.
Bag filters prepared from high dirt capacity polypropylene filter media sheets which have been sewn together are commercially available from Pall Corporation (Glen Cove, N.Y.) under the trademark Profile.RTM.. While such bag filters can be used in various end-uses and have a graded pore structure which provides for a high dirt capacity, the polypropylene bag filters are not suitable for use in certain environments, such as in the filtering of aluminum processing fluids where high oxidation conditions and aromatic liquids may be encountered.
Bag filters from other materials, such as polyester, have been prepared for use in the aluminum processing industry using a medium made from coarse fibered felt or of a woven construction. While such bag filters are suitable for use in high oxidation situations and/or with aromatic liquids, such bag filters are quite inferior to the polypropylene bag filters with graded pore structure with respect to pore ratings and dirt capacity.
There remains, therefore, a need for a bag filter which has a high dirt capacity and which is resistant to high oxidative conditions and aromatic solvents. Such a bag filter would prove particularly useful in filtering aluminum processing fluids which contain high amounts of aromatic solvents. Such a bag filter should also have seams constructed in such a manner so as not to allow the fluid being filtered to bypass the filter medium by way of the seams, while at the same time providing for a good mechanical bond at the bag filter seams. The present invention provides such a bag filter.